Post on 03-Jan-2016
description
Achieving Long-Term Surveillance
in VigilNetPascal A. Vicaire
Department of Computer Science
University of Virginia
Charlottesville, USA
Motivating Application: Battlefield SurveillanceTo
Satellite
Other Applications
Wildlife Monitoring
Alarm System
Flock Protection
Border Surveillance
Power Consumption: An Important Issue in Surveillance Systems No power management 4 days lifetime!
Power management 10 months lifetime!
State of the Art: Hardware
Power efficient hardware MICA2, MICAz, XSM, etc…
Energy scavenging hardware Vibrations. Roundy et al., “A Study of Low Level
Vibrations as a Power Source for Wireless Sensor Network”, Computer Communications, 2003.
Sun light. Perpetually powered Telos.
State of the Art: Software
Synchronization and coordination: Nodes turn on only for specific tasks of which the execution time is known in advance.
Data aggregation and compression: Nodes reduce amount of transferred data to decrease energy costs.
Coverage control: Nodes providing redundant sensing coverage are turned off.
Duty cycle scheduling: Nodes alternate between on and off states at a fast rate, which still allow them to detect slow paced targets.
Power Management in VigilNet Combination of three schemes in real system.
Duty CycleScheduling
TripwireService
SentryService
Node Level
Group Level
Network Level
Putting Nodes Into a Sleep State
Toggle Period
Sleep 1% Wakeup Sleep
Preamble length = TogglePeriod * BitRate SYNC Bytes DATA CRC
Putting nodes to sleep as often and as long as possible. Sleeping mode: node wakeup 1% of the time.
Wakeup operation: send message with long preamble.
(1s)
(10ms)
Group Level: Sentry Selection Redundant sensing coverage!
Group Level: Sentry Selection Sentry selection and rotation.
Asleep
Awake
Sentry
Group Level: Sentry Selection How are the sentries selected?
Group Level: Sentry Selection 1. Neighbors exchange “hello” message
(ID + position + nb of neighbors + energy).
Group Level: Sentry Selection 2. Each node selects a delay according to its
energy resources and coverage.
Delay = Function (Energy + Coverage)
Group Level: Sentry Selection 3. Once the delay is elapsed, a node
announces itself as a sentry.
Group Level: Sentry Selection Tradeoff: detection probability versus density.
TargetDetectionProbability
Number of Sentries inArea
10010 1,000
Sensing Radius=20mSensing Radius=8mSensing Radius=2m
Node Level: Duty Cycle Scheduling Target takes time to go through the network.
Node Level: Duty Cycle Scheduling Target takes time to go through the network
duty cycle scheduling.
Toggle Period (1s)
Asleep(800ms)
Awake (200ms)
Node Level: Duty Cycle Scheduling Putting it all together.
Asleep
Awake
Sentry
Node Level: Duty Cycle Scheduling Tradeoff: detection probability versus duty cycle.
Target DetectionProbability
Proportion of the TimeSentries are Awake
40%
100%
0% 20%
1000 Nodes, V=10m/s1000 Nodes, V=30m/s
Network Level: Tripwire Scheduling Exploiting knowledge about the target.
Network Level: Tripwire Scheduling Putting it all together.
Asleep
Awake
Sentry
Tripwire
Network Level: Tripwire Scheduling Each base station defines a tripwire; a node pertains
to the tripwire associated with the closest base.
Tripwire
Node
Base Station
Network Level: Tripwire Scheduling There are as many tripwires as base stations.
Tripwire
Node
Base Station
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
Network Level: Tripwire Scheduling Tripwire schedule specification:
Tripwire1
Tripwire2
Tripwire3
Tripwire4
Tripwire5
Tripwire6
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
1
0
0
1
0
0
0
1
0
0
1
0
0
0
1
0
0
1
On-Demand Wakeup
Wakeup PathTo Base StationFor Prompt Reporting
Detection Wakeup SurroundingNodes for Better Target Tracking, Target Classification,& Velocity Estimation
Asleep
Awake
Base Station
Evaluation Methodology
Field
XSMsTripwire 1 Tripwire 2
Tripwire 3
Evaluation Methodology
0
10
20
30
40
50
60
70
Time (seconds)
En
erg
y(m
w)
Sentry
NonSentry
Initialization Duration = 5 minutes
Surveillance Duration = 1day
Without system rotation:NonSentry Life Time: 250 daysSentry LifeTime: 7 daysEne
rgy
(mW
s)
Time (s)
Initialization
Surveillance
SentryNon-Sentry
Evaluation Results: Lifetime
0
50
100
150
200
250
300
350
No PM + Sentry + Duty Cycle + Tripwire
Lifetime (days)
Evaluation Results: Target Detection and Classification Average detection delay: 2.42 seconds. Average classification delay: 3.56 seconds. Classification of humans, humans with
weapons, and vehicles. Average delay to get velocity estimation:
3.75 seconds (average error: 6%).
Summary
Successfully integrate 3 power management strategies into real surveillance system having a 10 months lifetime (source code available online).
Analytical model to predict system performance under various system configurations.
Simulation results exposing tradeoffs between detection performance and lifetime of the network.
My Webpage: www.cs.virginia.edu/~pv9f
Tian’s Webpage:www.cs.umn.edu/~tianhe
Research Group Webpage:www.cs.virginia.edu/~stankovic/sensornet.html
Questions?